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Basic Anatomy & Physiology II Dr. L. Bacha

Chapter Outline (Marieb & Hoehn 6th edition)

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FEMALE REPRODUCTIVE SYSTEM

Anatomy of the Female Reproductive System

26.10 The external genitalia of the female include those structures that lie external to the vagina (( starts on page 911)

( the female reproductive structures that lie external to the vagina are called the external genitalia; they are also called the vulva or pudendum

( briefly describe the following components of the vulva and locate them in Fig. 26.17:

( mons pubis:

( labia majora (singular = labium majorum):

( labia minora (labium minorum is singular):

( vestibule - the vestibule is the space enclosed by the labia minora

( the openings of the vagina and urethra are in the vestibule

- name the opening of the vagina (named in Fig. 26.17):

- name the opening of the urethra (named in Fig. 26.17):

( vestibular glands release mucus into the vestibule; what is the function of the mucus?

( clitoris:

- what is it composed largely of?

- what is the exposed portion called?

- the glans clitoris is covered by a skin fold, the prepuce of the clitoris, which is formed by the junction of what?

- the clitoris is richly innervated with what?

( The Female Perineum

( the female perineum is a diamond shaped region located between

The pubic arch, coccyx, and ischial tuberosities

( located this area on Fig. 26.17 a

26.11 The mammary glands produce milk

( the mammary glands are modified sweat glands in the breasts (see Fig. 26.18)

( each consist of 15-25 lobes, with adipose tissue in between, that radiate around and open at the nipple

( within the lobes are several smaller units called lobules with milk-secreting glands

( milk is transported through ducts ending at the nipple

( the darker pigmented area around the nipple is called the areola

Internal Female Reproductive Organs ( (back to page 905)

26.8 Immature eggs develop in follicles in the ovaries

( The Ovaries

( the ovaries are paired, almond-shaped organs; they lie on each side of the upper pelvic cavity and are attached to the pelvic wall and uterus by ligaments

( the tunica albuginea is the capsule of CT that surrounds each ovary

( ovarian follicles are in the cortex of the ovary

- each follicle consists of an immature egg called what?

- each oocyte is surrounded by cells called follicle cells (when present in a single layer) and granulosa cells (when in several layers)

26.9 The female duct system includes the uterine tubes, uterus, and vagina

( The Uterine Tubes

( what are the uterine tubes also called?

( they are paired; approx. 4 inches long; they convey oocytes from the ovaries to the uterus

( 3 segments of the uterine tubes:

1. infundibulum

- the funnel-shaped open end near the ovary

- the infundibulum is fringed with fingerlike processes called fimbriae that extend from its free margin. Their movement creates currents in the peritoneal fluid that carry the oocyte into the uterine tube following ovulation.

2. ampulla - the middle segment; fertilization usually occurs in this segment

3. isthmus - the segment nearest that opens into the uterine cavity

( The Uterus

( the uterus is located in the pelvis; it is a hollow, thick-walled, muscular organ that does what?

( in women who have never been pregnant, the uterus is about the size and shape of what?

( describe the three parts of the uterus:

1. body –

( the space within the body of the uterus is the uterine cavity

2. fundus –

3. cervix –

( define cervical canal:

- the opening of the cervical canal into the vagina is the external os

- the opening of the cervical canal into the uterine cavity is the internal os

( the mucosa of the cervical canal contains cervical glands that secrete mucus

- please read about the functions of the cervical mucus!

The Uterine Wall (p. 909)

( there are three layers of the wall of the uterus; identify them on Figs. 26.15 and 26.16(a):

1. perimetrium

- the outermost layer; a serous membrane

2. myometrium

- the thick middle layer; what is it composed of?

3. endometrium:

- the mucosal lining; consists of simple columnar epithelium and underlying connective tissue, called stroma

- the epithelium invaginates to form uterine glands (endometrial glands)

-name and describe the two chief layers of the endometrium:

( read about the vascular supply of the uterus and Fig. 26.16(b)

( explain what the spiral arteries repeatedly do, and the significance during menstruation:

( The Vagina

( the vagina is a thin-walled tube, 8-10 cm long

( what are the functions of the vagina?

Physiology of the Female Reproductive System (( starts on page 913)

26.12 Oogenesis is the sequence of events that leads to the formation of ova

Oogenesis ((we will get back to most of this later!)

( define oogenesis ((from the glossary in the back of the book):

( examine Fig. 26.20 and my diagram below:

∙ is an oogonium haploid or diploid?

∙ is an ovum (egg) haploid or diploid?

∙ is a zygote haploid or diploid?

The Female Reproductive Cycle (The Menstrual Cycle)

( Hormonal Regulation of the Female Reproductive Cycle:

Hormones involved:

( GnRH = gonadotropin-releasing hormone

( produced in the hypothalamus of the brain

( stimulates the release of gonadotropins (LH and FSH) from the anterior pituitary

( gonadotropins -produced by the cells of the anterior pituitary (adenohypophysis):

FSH = follicle-stimulating hormone

( stimulates development of ovarian follicles

( stimulates the cells of the developing follicles in the ovaries to produce estrogen and progesterone

LH = luteinizing hormone

( stimulates ovulation

( stimulates remnants of the ruptured follicle in the ovary to differentiate into a corpus luteum

( stimulates the cells of the corpus luteum in the ovary to produce estrogen and progesterone

( estrogens

( secreted by cells of the developing follicles and the corpus luteum in the ovaries

( promote the proliferative phase of the uterus (and have numerous other functions; see Table 27.2 on page 1079)

( progesterone

( secreted mainly by the cells of the corpus luteum in the ovary

( promotes the secretory phase of the uterus

( Phases of the Female Reproductive Cycle:

During the female reproductive cycle (menstrual cycle), cyclic changes occur in the ovaries and uterus. Examine the timeline below, which uses an average of 28 days for the length of a menstrual cycle (although it typically varies from 24 to 35 days or so!):

ovulation

(

days

1 5 14 28

with reference

to the ovary:

Follicular Phase Luteal Phase

(Preovulatory Phase) (Postovulatory Phase)

with reference

to the uterus:

Menstrual Proliferative Phase Secretory Phase

Here is m summary of the menstrual cycle; we will follow what happens in the ovaries during the menstrual cycle, then we will follow the changes that occur in the uterus; we will do drawings in class to help show all! Ready….?

EVENTS IN THE OVARIES

First, review oogenesis (page 7 of these notes).

Before puberty, the ovary contains numerous primordial follicles that each contain a primary oocyte arrested in meiosis one.

( Follicular Phase (Preovulatory Phase)

• GnRH stimulates the anterior pituitary to release FSH and LH

• under the influence of mainly FSH, several primordial follicles begin to develop further; of those that begin to develop further, most die off (called atretic follicles)

• near the end of the follicular phase, typically only one follicle develops into a mature (Graafian) follicle

• about 4 hours before ovulation, the primary oocyte in the mature follicle completes meiosis I and becomes a secondary oocyte arrested in meiosis II; it will NOT complete meiosis II and become a haploid egg unless a sperm enters its cytoplasm just before fertilization!

• the follicular cells of the developing follicles secrete mainly estrogens (that effect the endometrium of the uterus)

( Ovulation

• usually occurs on day 14 of a menstrual cycle

• high levels of estrogens have a positive feedback effect, stimulating an increased secretion of GnRH from the hypothalamus and directly stimulating gonadotrophs of the anterior pituitary; as a result, there is a large surge in blood levels of LH and a smaller surge in FSH released by the anterior pituitary

• this causes the rupture of the mature (Graafian) follicle and the release of the secondary oocyte (surrounded by the zona pellucida and corona radiate) from the surface of the ovary (the ovulated oocyte and surrounding structures are swept into the uterine tube; we will follow what happens to them later!

( Luteal Phase (Postovulatory Phase)

• after ovulation, the remnant of the empty, collapsed follicle in the ovary differentiates into a corpus luteum (CL) under the influence of LH

• the CL secretes progesterone (and estrogens) that effect the endometrium of the uterus

• if the ovulated secondary oocyte is not fertilized, the CL in the ovary begins to degenerate about 10 to 12 days after ovulation (day 24 to 26 of the menstrual cycle) ( blood levels of estrogen and progesterone decrease and fail to “maintain” the endometrium ( menstruation occurs

• if fertilization does take place, the CL in the ovary persists due to the production of HCG (human chorionic gonadotropin) produced by cells of the trophoblast (that become the chorion) about 8 days after fertilization ( the CL in the ovary becomes the “CL of pregnancy” and produces higher levels of progesterone and estrogens ( this maintains the endometrium and brings about many of the changes that occur in pregnancy

EVENTS IN THE UTERUS

( Menstrual Phase (Menstruation)

• occurs during the first 3 to 5 days of a menstrual cycle

• if the ovulated secondary oocyte is not fertilized (more often than not that is the case!), the CL in the ovary begins to degenerate (it “regresses”) about 10 to 12 days after ovulation (day 24 to 26 of the menstrual cycle) ( blood levels of estrogen and progesterone decrease ( low blood levels of these hormones fail to “maintain” the endometrium of the uterus, and menstruation occurs:

- the stratum functionalis degenerates, breaks up and sloughs away

• menstrual flow contains:

∙ degenerated endometrial cells

∙ blood from vessels of the endometrium

∙ mucus from the cervix and vagina

• the beginning of menstrual flow marks the beginning (day 1) of a new menstrual cycle

• at the end of the menstrual phase, only the thin stratum basalis of the endometrium remains

( Proliferative Phase

• after menstruation, the endometrium is very thin, with only the stratum basalis remaining

• increasing blood levels of estrogen produced by cells of the developing follicles in the ovaries stimulate the stratum basalis to produce a new stratum functionalis, and the endometrium thickens (“builds up”):

- the endometrium glands develop

- blood vessels in the stroma lengthen

( Secretory Phase

• the endometrium “builds up” further, due mainly to the stimulation of progesterone (and estrogens) produced by the corpus luteum in the ovary:

- the endometrial glands develop further; they lengthen, become tortuous, and become swollen with a nourishing secretion of lipids and glycogen

- blood vessels in the stroma lengthen further

Hormonal Regulation of the Menstrual Cycle

GnRH = gonadotropin releasing hormone:

produced by neurons of the hypothalamus of the brain; stimulates the release of the gonadotropins (LH and FSH) from the anterior pituitary gland

gonadotropins -produced by the cells of the anterior pituitary gland:

LH = luteinizing hormone and FSH = follicle stimulating hormone

FOLLICULAR PHASE (PREOVULATORY PHASE) of the OVARY

MENSTRUATION AND PROLIFERATIVE PHASE of the UTERUS

1. Hypothalamus ( GnRH

2. GnRH stimulates anterior lobe of pituitary gland ( FSH & LH

3. FSH ( development of ovarian follicles

4. Follicle cells ( estrogens & progesterone

5. Estrogens ( stimulates proliferation of the endometrium

6. Increasing levels of estrogen & progesterone ( negative feedback on the hypothalamus to decrease secretion of FSH & LH

OVULATION

7. Steadily increasing blood levels of estrogen & progesterone late in the follicular phase

( positive feedback on the hypothalamus ( ( GnRH from the hypothalamus

( rapid, large ( LH (LH surge) & smaller ( FSH (FSH surge) from the anterior pituitary gland ( ovulation

LUTEAL PHASE (POSTOVULATORY PHASE) of the OVARY

SECRETORY PHASE of the UTERUS

8. Hypothalamus ( GnRH

9. Anterior lobe of the pituitary stimulated by GnRH ( FSH & LH

10. LH ( stimulates development of corpus luteum (CL) from the remnants of the collapsed follicle in the ovary following ovulation

11. CL ( estrogens & progesterone

12. Estrogens and progesterone ( further development of the endometrium

13. Increasing blood levels of estrogens & progesterone

( negative feedback on the hypothalamus ( ( GnRH from the hypothalamus

( ( FSH & ( LH from the anterior pituitary gland

( with a ( LH, there is regression of CL (approx. day 24-26)

( ( estrogen & ( progesterone

( low blood levels of estrogen & progesterone fail to maintain the endometrium and fail to stimulate further development of the endometrium

( MENSTRUATION (day 1)

If fertilization occurs, the embryo secretes HCG (human chorionic gonadotropin), which prevents the CL from degenerating and it stimulates further development of the CL in the ovary. The CL becomes the “CL of Pregnancy”, and produces increasing levels of estrogens and progesterone, and menstruation does not occur.

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CJ(OJQJU[pic]^JaJmHnHu[pic]hÌsÄh |RO the area between the vaginal orifice and the anus It may be torn during childbirth. To prevent damage and ensure proper healing, a surgical incision, called an episiotomy, is often made in the perineum to enlarge the vaginal opening for delivery.)

The End!

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